The infirmary smelled of antiseptic and something else. Something metallic and bitter, like a snapped guitar string still humming with tension. Kaelen Vance resisted the urge to straighten the medical chart Isabelle had shoved into her hands. The ink—standard Clave-issue, prone to smudging—had feathered at the edges of the page, a tiny imperfection that set her teeth on edge.
Alec Lightwood sat on the edge of an examination cot, spine rigid, his gaze fixed on the far wall. He wore only grey uniform trousers, his torso bare to the unforgiving fluorescent lights. The rune was worse than Isabelle’s frantic fire-message had described.
It wasn’t just faded or blurred. The *parabatai* rune, high on his right side, was the epicentre of a creeping blight. Veins of pure black, thin as captured threads of shadow, radiated from its edges, branching across his ribs and creeping toward his shoulder. It wasn’t a mark *on* his skin. It was *in* his skin, a latticework of darkness pulsing with a slow, sickly rhythm.
“He won’t let Magnus near it,” Isabelle said, her voice tight. She stood with her arms crossed, a living statue of fury and fear. Her whip was coiled at her hip, but her hands were clenched into fists. “He says it’s… a Shadowhunter matter.”
Kaelen didn’t look up from the rune. “And you believe him?”
“I believe he’s in pain and deflecting,” Isabelle bit out. “Can you fix it?”
“I don’t know what ‘it’ is,” Kaelen said, her voice studiously calm. She was a Scribe, a Runic Scholar. Her job was to understand, not to perform miracles. “This isn’t entropic decay. It isn’t demonic corruption, not any strain I’ve ever catalogued. The patterns are too… deliberate.”
She stepped closer. Alec flinched, a bare tightening of his jaw. He didn’t look at her.
“Alec,” she said softly. “I need to touch it.”
“Don’t.” The word was gravel.
“I can’t analyze the energy signature from a metre away.”
He finally turned his head, and the despair in his eyes was a physical blow. “There’s nothing to analyze. It’s my fault. I just have to bear it.”
“Don’t be an idiot,” Isabelle snapped. “You came back from patrol like this. You didn’t *do* anything.”
Kaelen noted the omission. Not what happened *on* patrol, just that he came back *from* it. Isabelle was hiding the trigger. Fine. Let her. The runes told their own story.
“I need a reflective surface,” Kaelen announced, turning to Isabelle. “Not a mirror. Something polished. A silver platter from the kitchens, maybe.”
Isabelle’s brow furrowed, but she left without a word. Kaelen had spent her life cataloguing the vagaries of angelic symbols; she had no intention of inviting the chaotic distortions of a looking glass into the process. Mirrors lied. Silver, at least, was honest.
“It hurts when you breathe, doesn’t it?” Kaelen asked the silent room.
Alec’s posture stiffened further. A confession.
“Like breathing in powdered glass,” she continued, her eyes tracing the path of one black tendril as it neared his collarbone. “And there’s a sound. A high, thin whine, just at the edge of your hearing.”
His head whipped around, his eyes wide with shock. “How…”
Before she could answer, the black veins flared, pulsing with a sudden, violent light. Alec cried out, a sharp, strangled sound, and curled in on himself, clutching his side. The metallic scent in the air intensified, acrid and hot.
Isabelle burst back in, a silver serving tray in her hands. She dropped it on a nearby table with a clatter and rushed to her brother’s side. “Alec! What’s happening?”
He couldn’t answer, his teeth gritted, a sheen of sweat on his forehead.
Kaelen made a decision. Observation was over. This was active escalation. She strode to her own satchel, a worn leather bag filled with vellum scrolls and specialized tools. She bypassed the sterile scalpels and diagnostic crystals, her fingers closing around a stick of coarse, grey chalk. Scrying chalk. Volatile, single-use, and strictly forbidden for field application by the Clave. It didn’t interact with runes so much as it agitated them, forcing the magical signature to reveal its foundational nature. A diagnostic scream.
“What’s that?” Isabelle demanded, her hand on Alec’s unmarred shoulder.
“A risk,” Kaelen said, uncapping it. She knelt on the floor beside the cot. She didn’t touch Alec. Instead, she began to draw a circle on the cold linoleum *around* his arm, her movements swift and precise. It was a simple containment rune, one taught to first-year Scribes to keep ink from bleeding on vellum.
The moment she closed the circle, the chalk began to smoke.
The black veins on Alec’s skin writhed. The faint humming in the room rose to an audible, dissonant chord. Alec gasped, his back arching off the cot.
“Kaelen, stop it! You’re hurting him!” Isabelle yelled.
“It’s working,” Kaelen breathed, her eyes locked on the rune.
The chalk line on the floor glowed with a fierce white light. The light didn’t touch Alec, but the corruption responded. The intricate black lines, the chaotic spidery veins, began to shift. They pulled inward, the energy dragging them into a new configuration against their will. For a single, horrifying second, the chaos resolved.
Inside the boundary of the original *parabatai* rune, the black energy formed a perfect, unmistakable shape.
A single, barbed feather.
Then, with a sound like cracking stone, the chalk circle on the floor shattered into dust. The feather marking dissolved back into its web of chaotic lines. Alec slumped back onto the cot, conscious but shaking, the sweat on his skin now cold.
The room was silent, save for his ragged breathing. Kaelen stared at the dust on the floor, then at the corrupted rune, now settled back into its ugly, sprawling pattern. She had seen demonic sigils, angelic script, the marks of fey bargains and warlock pacts. She had never, in any text, in any archive, seen anything like that.
She looked at Alec, truly looked at him, and the scholar’s detachment she held so dear evaporated, replaced by a cold, sharp spike of dread. This wasn’t a corruption she could catalogue. This was an intrusion.